I'm thinking about my spring and summer wardrobe and I haven't many options for warmer weather. I have a few T-shirts that are still looking alright, but most of my tees and tanks right now are only suitable for layering (or look very casual).

I'm not sure I want to wear exclusively T-shirts, it might be time time to branch out a bit. But I have a serious aversion to polyester and other synthetics, so that makes it quite difficult to find dressier looking tops nowadays. And I would love to continue to shop eco brands whenever possible and the one thing you can find there in abundance are cotton tees... Other natural fabrics are often quite expensive.

I need some inspiration. Any ideas what to look for? Or should I just stick to my casual tees?

ETA

Update 1